Application and design of LM4702 power amplifier module

LM4702 power amplifier module Application and design solution

This is the first product in a new high-performance audio chip series with a wide supply voltage range, mute function and multiple protection functions. It is suitable for advanced home audio systems and meets the strict requirements of professional-grade audio equipment.

IC LM4702 (Figure 1). LM4702 pdf datasheet The LM4702 chip is actually an audio power amplifier driver IC suitable for high supply voltage. It contains two independent audio amplification and driving parts. As long as a small number of external components are connected, a high-performance audio power amplifier can be formed. The LM4702 can drive multiple high-power discrete transistors or multiple pairs of Darlington transistors. It is suitable for systems that can provide 25W to 300W output power per channel. Its typical application circuit is shown in Figure 2. On the homepage of National Semiconductor, you can download application design data (http://www.national.com/an/AN/AN-1490.pdf). When this circuit is in the best working state, the total harmonic distortion and noise (THD+N) is only 0.0006%. The designer can adjust the output power of the amplifier by changing the supply voltage and the related output power transistors. For high current and power applications, the output stage can adopt a multi-tube parallel configuration without changing the basic circuit of the LM4702 driver. The LM4702 chip is equipped with an advanced overheat protection circuit. If the chip temperature reaches 150°C or above, the protection circuit will be activated. In addition, this driver also has a mute function that can suppress switching noise. When this function is activated, the output of the amplifier can be reduced to the equivalent quiescent current state. This function can be easily designed into the standby state of the amplifier.